Absorbent pads are well-known and widely used in the food industry. One type of absorbent pad is used as a biofluid absorber and is placed between fresh meat and the plastic meat tray. The pad functions to absorb biofluids exuding from the meat.
A second type of known pad is used as a cooling pad and is initially swelled with water, frozen and then placed with food or other produce which is to be kept cool.
Both types of pads have internal absorbents and typically use superabsorbent polymers (SAP). These polymers are also well-known and a typical polymer is a cross-linked sodium polyacrylate. In order to allow the internal absorbent to absorb fluid efficiently, the polymer is usually finely ground.
The internal superabsorbent polymer creates some difficulties which must be overcome if the pad is to be safe and commercially successful. Firstly, it is necessary to ensure that the polymer stays within the pad at all times, even when swollen into a gel-like state. Another problem with the superabsorbent polymers is that they are aggressive fluid absorbers and tend to desiccate the meat product by absorbing more than just the exuded biofluids.
To overcome the aggressive absorbing nature of the polymer, it is known to have absorbent pads formed with a bottom wall which is water permeable (and is typically a non-woven fabric), and a top wall formed from a totally liquid impermeable sheet.
A disadvantage with having a liquid impermeable top sheet is that biofluids run over the top sheet and fall away from the pad without the pad being able to absorb the biofluid through the bottom layer. This is particularly so if the meat product tray is stored or presented at an angle. Another disadvantage with the impervious top layer is that if the meat tray is level, biofluids can pool on the top layer and ruin the meat by promotion of bacterial growth.
Attempts have been made to provide a large slit or a number of slits in the top wall of the pad to overcome the above disadvantage. However the biofluids are still not efficiently absorbed and have a tendency to run off the top sheet, or to pool.
Another problem with cooling pads is that when the pads are swollen with water, the superabsorbent polymer turns into a gel and exerts considerable pressure on the wall of the pad and can extrude through the pad wall. This is particularly so if the top wall of the pad is formed with a large slit or slits.